A recent WHO report has stated that there are 39.5 million people currently HIV positive worldwide. Of these, 4.3 million were infected in the year 2006 alone. AIDS deaths reached 2.9 million in 2006, which is the highest ever reported in any year. This number would have been even higher but for the recent progress made in providing the highly active antiretroviral therapy (HAART) to a large population of AIDS patients in underdeveloped countries. Nevertheless, there are still 40,000 new AIDS cases a year in the U.S. even with the HAART. Thus, alarmingly AIDS is on the rise worldwide (1).
Great effort has been focused on development of HIV-preventive vaccine during the past 20 years. However such vaccine research has met with unusual obstacles. As described in a recent article by Robert Gallo (2), it is not appropriate to develop HIV vaccines using attenuated live HIV because of the inherent danger of causing AIDS. Furthermore, there is no useful small animal model for studying HIV infection. The SIV/monkey model, while offering limited information on the mode of viral actions, is expensive in operation and generally not available to investigators. From many studies, we have also learned that the gp120 based HIV vaccine was not overly effective, and does not protect all strains of viruses containing highly variable regions of the V3 loops. In addition, all recombinant HIV strains occur in vivo at an exceedingly fast rate.
The anti HIV compounds that are currently being used to treat AIDS patients include several reverse transcriptase inhibitors: zidovudine, didanosine, zalcitabine, stavadine, lamivudine and nevirapapine; and protease inhibitors: saquinavir, ritonavir, indinavir and others. It has recently been observed that these drugs, while very potent suppressers of wild type viruses, gradually lose their effectiveness with the appearance of a group of populated viral mutants.
Thus, the development of alternative therapeutic methods that inhibit HIV infection and protect host cell mediated immunity (CMI) is urgently needed.